Aging increases the risk of neurodegeneration. Strong evidence implicates aggregation-mediated proteotoxicity as the cause of neurodegeneration in numerous clinically important diseases, including Alzheimer's disease, although the mechanism remains unclear. Emerging genetic data suggest that the aging process is linked by signalling pathways to the fidelity of protein folding, including the ability to recover or dispose of misfolded or aggregated proteins. Overall this program project strives to meet two goals. First, to understand the organismal, cell biological and molecular bases for the pathways that protect organisms from protein misfolding, and second, to determine how these pathways become compromised as an organism ages. The Kelly Laboratory will focus on four specific aims related to the key questions outlined directly above. These are: (1) to utilize biological and chemical approaches to identify and characterize the pathway(s) and the underlying molecular determinants of the fractionatable and separable disaggregation and proteolysis activities that appear to protect against age onset proteotoxicity in C. elegans models (in collaboration with the Dillin, Yates and Balch Laboratories);(2) to do the same with mouse AD models and mammalian cell lines, and to compare the results from these systems to the results obtained from C. elegans (also in collaboration with the Dillin, Yates and Balch Laboratories);(3) to employ biological and chemical approaches and especially immunoelectron microscopy to discern the subcellular location of Abeta aggregates in daf-2 RNAi or hsf-1 RNAi treated, Abeta-expressing worms, as well as to scrutinize the hypothesis that there is an active aggregation pathway or activity as implied from genetic data (in collaboration with the Balch, Dillin and Bannykh Laboratories), although other explanations for the data are possible;and (4) to test the hypothesis that amyloidogenesis is constitutive in the Borchelt Alzheimer's murine model long before Abeta fibrils are detectable immunohistochemically or behavioral phenotypes are observed, i.e., that amyloidogenesis happens as a consequence of the inherent inefficiencies in protein homeostasis (a subhypothesis is that constitutive amyloidogenesis only becomes toxic when the detoxification pathway(s) or activities drop below a threshold level due to organismal aging) (in collaboration with the Dillin, Balch, Bannykh and Masliah Laboratories).